diff options
| author | Eric Dumazet <edumazet@google.com> | 2018-09-13 07:58:50 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-19 22:43:46 +0200 |
| commit | 48c2afc16888873da727f9ed7102a620a178fad8 (patch) | |
| tree | d17adc2d92d2247be1c3e1b55ed43666a06f05e4 /include | |
| parent | 8291cd943a9b4e2d764a4a294999bbb2f94f153c (diff) | |
inet: frags: get rid of ipfrag_skb_cb/FRAG_CB
ip_defrag uses skb->cb[] to store the fragment offset, and unfortunately
this integer is currently in a different cache line than skb->next,
meaning that we use two cache lines per skb when finding the insertion point.
By aliasing skb->ip_defrag_offset and skb->dev, we pack all the fields
in a single cache line and save precious memory bandwidth.
Note that after the fast path added by Changli Gao in commit
d6bebca92c66 ("fragment: add fast path for in-order fragments")
this change wont help the fast path, since we still need
to access prev->len (2nd cache line), but will show great
benefits when slow path is entered, since we perform
a linear scan of a potentially long list.
Also, note that this potential long list is an attack vector,
we might consider also using an rb-tree there eventually.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit bf66337140c64c27fa37222b7abca7e49d63fb57)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/skbuff.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 6dd77767fd5b..f4749678b7ee 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -678,6 +678,7 @@ struct sk_buff { * UDP receive path is one user. */ unsigned long dev_scratch; + int ip_defrag_offset; }; /* * This is the control buffer. It is free to use for every |